JP2020041512A - Compression cylinder - Google Patents

Abstract

To provide a compression cylinder with a small load onto a rod packing for sealing an outer periphery of a rod.SOLUTION: A compression cylinder comprises a cylinder tube 10 communicated with a suction port 20 and an emission port 30, a piston 1 tightly and slidably arranged in the cylinder tube 10, a coupling shaft 4 integrally coupled coaxially with the piston 1, having a smaller diameter than that of the piston 1, and tightly slidable in a coupling tube 12 formed coaxially with the cylinder tube 10, a rod 5 coupled with the coupling shaft 4 and transmitting a driving force to the piston 1 via the coupling shaft 4, a rod packing 6 sealing an outer periphery of the rod 5, and a communication hole 12b communicating a space in the coupling tube 12 between a rear end 4b of the coupling shaft 4 and the rod packing 6 to outside. Gas supplied from the suction port 20 is compressed in the cylinder tube 10 by the piston 1, and fed from the emission port 30.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a compression cylinder, and more particularly, to a compression cylinder in which a load on a rod packing for sealing an outer periphery of a rod is small.

  Patent Document 1 describes a reciprocating compressor. In such a reciprocating compressor, there is a compressor in which a supplied gas is compressed by a compression cylinder in which a cylindrical piston is slidably disposed in a cylindrical cylinder.

JP 2017-026044 A

  By the way, in the cylinder cylinder, the internal pressure pulsates greatly between the suction pressure and the compression pressure due to the movement of the piston. This pressure pulsation is also applied to the rod packing that seals the outer periphery of the rod, and the rod packing is subjected to a large load due to vibration, impact, and sliding friction heat to shorten the life.

  Therefore, an object of the present invention is to provide a compression cylinder in which a load on a rod packing for sealing the outer periphery of the rod is small.

  Other objects of the present invention will become apparent from the following description.

  The above object is achieved by the following inventions.

1.
A cylinder cylinder communicated with the suction port and the discharge port,
A piston disposed slidably in the cylinder cylinder,
A connecting shaft which is coaxially and integrally provided with the piston, has a smaller diameter than the piston, and is capable of closely sliding within a connecting cylinder formed coaxially with the cylinder cylinder;
A rod that is connected to the connection shaft and transmits a driving force to the piston via the connection shaft;
Rod packing for sealing the outer periphery of the rod,
A communication hole for communicating a space inside the connection cylinder between the rear end of the connection shaft and the rod packing outward.
A compression cylinder, wherein the gas supplied from the suction port is compressed by the piston in the cylinder cylinder and sent out from the discharge port.
2.
The space in the connection cylinder between the rear end of the connection shaft and the rod packing communicates outward through the communication hole, thereby reducing the pressure of the gas discharged from the discharge port. 2. The compression cylinder according to the above 1, wherein the pressure is low and higher than the atmospheric pressure.
3.
3. The compression cylinder according to claim 1 or 2, wherein the rod packing does not require supply of lubricating oil.
4.
The compression according to any one of claims 1 to 3, wherein a piston ring is mounted on an outer peripheral surface of the connection shaft, and an outer peripheral portion of the piston ring slides in close contact with an inner peripheral surface of the connection cylinder. Cylinder.
5.
Inside the cylinder cylinder, a cylindrical cylinder liner is mounted,
A piston ring and a rider ring are mounted on an outer peripheral surface of the piston, and an outer peripheral portion of the piston ring and the rider ring slides in close contact with an inner peripheral surface of the cylinder liner. The compression cylinder according to any one of the above.
6.
The compression cylinder according to any one of the above items 1 to 5, wherein the gas is used at 200 bar or more.

  ADVANTAGE OF THE INVENTION According to this invention, the compression cylinder with little load on the rod packing which seals the outer periphery of a rod can be provided.

Sectional view showing the configuration of the compression cylinder of the present invention. The side view which shows the structure of the piston of the compression cylinder of this invention. Longitudinal sectional view showing the structure of the rod packing of the compression cylinder of the present invention. FIG. 2 is a block diagram schematically illustrating a compressor configured using the compression cylinder of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a sectional view showing the configuration of the compression cylinder of the present invention.

  As shown in FIG. 1, the compression cylinder of the present embodiment includes a cylinder cylinder 10, a cylinder liner 11 disposed in the cylinder cylinder 10, and a piston disposed in the cylinder liner 11 so as to be able to slide closely. 1 is a compression cylinder that compresses gas supplied from the suction port 20 via the suction valve 20a by the piston 1 in the cylinder cylinder 10 and sends out the gas from the discharge port 30 via the discharge valve 30a.

  The inside of the cylinder tube 10 is formed in a cylindrical shape, and a cylindrical cylinder liner 11 is fitted therein. The cylinder liner 11 need not be provided if the inner surface of the cylinder cylinder 10 has sufficient strength and durability. The cylinder cylinder 10 communicates with the suction port 20 and the discharge port 30 on the rear end side (left end side in FIG. 1). The front end (right end in FIG. 1) of the cylinder tube 10 is closed by a cylinder cover 10a. The space in the cylinder cylinder 10 between the front end (the right end in FIG. 1) 1a of the piston 1 and the cylinder cover 10a communicates outward (gas suction side) via a communication hole 10b.

  FIG. 2 is a side view showing the structure of the piston of the compression cylinder of the present invention.

  As shown in FIG. 2, the piston 1 is formed in a cylindrical shape that can be fitted inside the cylinder liner 11. A plurality of annular piston rings 2a are externally fitted to the piston 1. A rider ring 2b is externally fitted to the front end side (the right end side in FIGS. 1 and 2) and the base end side (the left end side in FIGS. 1 and 2) of the piston 1. The outer peripheral portions of the piston ring 2a and the rider ring 2b slide in close contact with the inner peripheral surface of the cylinder liner 11. Note that the piston ring 2a and the rider ring 2b may be replaced with various types of sealing members as long as sufficient strength and durability are ensured, and these sealing members may be replaced by, for example, a labyrinth seal. It is not necessary to provide.

  When the piston 1 slides in the cylinder liner 11 in the axial direction of the cylinder cylinder 10 (arrow A in FIG. 1), the gas in the cylinder cylinder 10 (in the cylinder liner 11) is compressed. In the cylinder cylinder 10 (inside the cylinder liner 11), the internal pressure varies greatly depending on the direction of movement of the piston 1. When the moving direction of the piston 1 is a direction in which the volume in the cylinder 10 is increased (rightward in FIG. 1), the pressure in the cylinder 10 decreases, and the moving direction of the piston 1 is changed to the volume in the cylinder 10. Is smaller (left direction in FIG. 1), the pressure in the cylinder 10 increases. At this time, the gas in the cylinder 10 is compressed.

  A connecting shaft 4 is coaxially and integrally connected to a base end (left end in FIGS. 1 and 2) 1b of the piston 1. The connecting shaft 4 is formed in a cylindrical shape having a smaller diameter than the piston 1. An annular piston ring 4 a is externally fitted to the connection shaft 4. The outer peripheral portion of the piston ring 4a slides on the inner peripheral surface of the connecting cylinder 12 formed coaxially with the cylinder cylinder 10. That is, the connection shaft 4 can be closely slid in the connection tube 12.

  The space in the connecting cylinder 12 (the space around the rod 5) between the rear end 4b of the connecting shaft 4 and the rod packing 6 is communicated outward through a communication hole 12b. The space between the rear end 4b of the connecting shaft 4 and the rod packing 6 is made to communicate with the outside so that the pressure is lower than the pressure of the gas discharged from the discharge port 30 and higher than the atmospheric pressure. Is preferred. In this case, such a pressure can be obtained by connecting the communication hole 12b to the gas suction side. However, it may be connected to a discharge port of another compressor.

  When the space between the rear end 4b of the connecting shaft 4 and the rod packing 6 is communicated outward (gas suction side) by the communication hole 12b, the rear end 4b of the connecting shaft 4 and the rod packing 6 Can be made equal to the suction pressure, the fluctuation can be suppressed, the load on the rod packing 6 can be reduced, and the supply of lubricating oil between the rod 5 and the rod packing ring 6a becomes unnecessary. can do.

  Note that the close contact between the outer peripheral surface of the connecting shaft 4 and the inner peripheral surface of the connecting cylinder 12 is not limited to the configuration using the piston ring 4a, and various methods can be used as long as sufficient strength, durability and sealing properties are ensured. Alternatively, the outer peripheral surface of the connecting shaft 4 may be directly in close contact with the inner peripheral surface of the connecting cylinder 12 without providing a sealing member. Further, the sealing member may be provided not on the outer peripheral surface of the connecting shaft 4 but on the inner peripheral surface of the connecting cylinder 12.

  As shown in FIG. 2, a rod 5 that transmits driving force to the piston 1 via the connecting shaft 4 is connected to a rear end (the left end in FIGS. 1 and 2) 4 b of the connecting shaft 4. . The outer periphery of the rod 5 is sealed by a rod packing 6 as shown in FIG.

  FIG. 3 is a longitudinal sectional view showing the structure of the rod packing of the compression cylinder of the present invention.

  As shown in FIG. 3, the rod packing 6 has a plurality of rod packing rings 6a for sealing the outer periphery of the rod 5, and a plurality of ring cups 6b accommodating the rod packing rings 6a. . Sliding friction between the rod packing ring 6a and the rod 5 generates sliding friction heat. This sliding friction heat is transmitted to the ring cup 6b.

  In this compression cylinder, since the connecting cylinder 12 sealed by the connecting shaft 4 is provided between the cylinder cylinder 10 and the rod packing 6, a high pressure in the cylinder cylinder 10 may be applied to the rod packing 6. Absent. Therefore, even if the pressure in the cylinder cylinder 10 pulsates between the suction pressure and the discharge pressure, the load on the rod packing 6 does not increase, and the vibration, impact and sliding frictional heat generated in the rod packing 6 are small. Therefore, the load on the rod packing 6 for sealing the outer periphery of the rod 5 is small, and the life can be prolonged.

  Further, since the rod packing 6 has small vibration, impact and sliding friction heat generated in the rod packing 6, it is not necessary to supply lubricating oil between the rod 5 and the rod packing ring 6a. In this case, it is possible to prevent the lubricating oil from being mixed into the compressed gas.

  Further, in this compression cylinder, by forming the piston rings 2a, 4a and the rider ring 2b from a material having high heat resistance, it is not necessary to supply oil to the piston 1. Alternatively, in this compression cylinder, by providing a cooling mechanism for circulating a cooling liquid, heat of the piston 1, the piston ring 2a, the rider ring 2b, the cylinder tube 10 and the cylinder liner 11 is absorbed, and the outside of the cylinder tube 10 By radiating heat, the inside of the cylinder tube 10 is cooled, and oil supply to the piston 1 can be made unnecessary.

  The rod packing 6 may be configured to distribute and supply the refrigerant from the refrigerant supply path 6c to the flow paths in each ring cup 6b, and collect and discharge the refrigerant from these flow paths to the refrigerant discharge path 6d. Good. The coolant supply passage 6c communicates with the outside at the coolant supply port 6e, penetrates through each ring cup 6b, branches in each ring cup 6b, and communicates with a flow path in each ring cup 6b. The refrigerant discharge passage 6d communicates from the flow path in each ring cup 6b, gathers in each ring cup 6b, penetrates through each ring cup 6b, and communicates outside at a refrigerant discharge port 6f. By supplying a coolant to the flow path in each ring cup 6b, a large amount of sliding friction heat can be removed, and the durability of the rod packing 6 can be increased.

[Configuration example of compressor]
FIG. 4 is a block diagram schematically showing a compressor constituted by using the compression cylinder of the present invention (showing an example in which there is a need to supply lubricating oil because there is reliquefaction).

  The compressor 200 using the compression cylinder of the present invention may have one stage, but as shown in FIG. 4, as an example, a plurality (for example, five) of compression stages 201 and 202 each having a compression cylinder. , 203, 204, and 205, and gradually compresses the gas in each of the compression stages 201, 202, 203, 204, and 205 to increase the pressure. In the latter stage (for example, the fourth stage) of the plurality of compression stages 201, 202, 203, 204, 205, the gas is already at a high pressure of 100 bar (10 MPa) or more.

  In a cylinder for compressing a high-pressure gas of 100 bar (10 MPa) or more to, for example, 200 bar or more, conventionally, the resin seal rings (piston ring and rod packing ring) of the piston 1 and the rod packing 6 have a short life due to high heat. May be caused. Under a low pressure, the resin seal ring can maintain a practical life even when lubrication oil supply is unnecessary. However, for example, when LNG boil-off gas is compressed into fuel gas for a marine engine, five-stage compression is necessary. In the fifth stage, the suction pressure is 100 to 120 bar and the discharge pressure is 200 bar. Under high pressure conditions, such as at or above a bar, there is a possibility that the practical life of the resin seal ring cannot be maintained if the supply of lubricating oil is unnecessary.

  The compression cylinder of the present invention does not require oiling to the rod packing when used in any of the compression stages 201, 202, 203, 204, and 205, and does not require oiling to the piston if provided with a cooling mechanism. be able to. In this case, in the compressor 200, there is no possibility that the compressed gas is contaminated by the lubricating oil. Therefore, it is possible to re-liquefy and reuse the gas that has passed through the subsequent compression stage at a very low temperature and high pressure. That is, the compression cylinder of the present invention is particularly useful for use under high pressure (for use in which a gas already at a high pressure (for example, 100 bar or more) is further raised to a higher pressure (for example, 300 bar or more)).

  The compressor 200 is applicable to any use. For example, in a use for compressing natural gas, the natural gas that has passed through the last compression stage 205 can be returned to the storage tank 206. Further, a check valve is not required before the subsequent compression stage (between the fourth stage 204 and the fifth stage 205).

  In addition, high-pressure hydrogen gas used for heavy oil desulfurization is used while containing oil because it is not possible to eliminate the need for supplying lubricating oil because of high pressure. Although this shortens the life of expensive catalysts in the reactor, high pressure hydrogen gas containing oil is used at present. If this becomes high-pressure hydrogen gas containing no oil, the catalyst life can be extended, which is a great merit.

  The present invention is not limited to the embodiments described above, and various improvements and design changes may be made without departing from the spirit of the present invention.

  In addition, it goes without saying that specific detailed structures, numerical values and the like and control contents of the control device can be appropriately changed. In addition, the embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Piston 1a Front end 1b Base end 2a Piston ring 2b Lidar ring 4 Connecting shaft 4a Piston ring 4b Rear end 5 Rod 6 Rod packing 6a Rod packing ring 6b Ring cup 6c Refrigerant supply path 6d Refrigerant discharge path 6e Refrigerant supply port 6f Refrigerant outlet 10 Cylinder cylinder 10a Cylinder cover 10b Communication hole 11 Cylinder liner 12 Connecting cylinder 12b Communication hole 20 Suction port 20a Suction valve 30 Discharge port 30a Discharge valve 200 Compressor 201 First compression stage 202 Second compression stage 203 Third Compression stage 204 fourth compression stage 205 fifth compression stage 206 storage tank

Claims (6)

A cylinder cylinder communicated with the suction port and the discharge port,
A piston disposed slidably in the cylinder cylinder,
A connecting shaft which is coaxially and integrally provided with the piston, has a smaller diameter than the piston, and is capable of closely sliding within a connecting cylinder formed coaxially with the cylinder cylinder;
A rod that is connected to the connection shaft and transmits a driving force to the piston via the connection shaft;
Rod packing for sealing the outer periphery of the rod,
A communication hole for communicating a space inside the connection cylinder between the rear end of the connection shaft and the rod packing outward.
A compression cylinder, wherein the gas supplied from the suction port is compressed by the piston in the cylinder cylinder and sent out from the discharge port.   The space in the connection cylinder between the rear end of the connection shaft and the rod packing communicates outward through the communication hole, thereby reducing the pressure of the gas discharged from the discharge port. 2. The compression cylinder according to claim 1, wherein the pressure is lower than the atmospheric pressure.   The compression cylinder according to claim 1, wherein the rod packing does not require supply of lubricating oil.   The piston ring is mounted on an outer peripheral surface of the connecting shaft, and an outer peripheral portion of the piston ring slides in close contact with an inner peripheral surface of the connecting cylinder. Compression cylinder. Inside the cylinder cylinder, a cylindrical cylinder liner is mounted,
A piston ring and a rider ring are mounted on an outer peripheral surface of the piston, and an outer peripheral portion of the piston ring and the rider ring slides in close contact with an inner peripheral surface of the cylinder liner. 5. The compression cylinder according to any one of 4.   6. The compression cylinder according to claim 1, wherein the gas is used at 200 bar or more.

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